Instrumentation

The regional moorings hold a range of instrumentation including acoustic doppler current profilers (ADCPs), WetLabs Water Quality Meters (WQMs), fluorometers, CTDs with turbidity and dissolved oxygen sensors. The National Reference Stations also collect samples for nutrients, ppCO2, dissolved inorganic carbon, total alkalinity, and plankton measurements. 

Schematic of Rottnest National Reference Station moorings

Moored instruments on the Western Australia moorings.

Instrument Moorings
SBE39 temperature logger NRSROT, NRSEP, WACA20, WACANO, WACASO, WATR05, WATR10, WATR15, WATR20
SBE37 CTD WATR10
Workhorse NRSROT, NRSESP, WATR15
Long Ranger RDI ADCP WATR50
Aquadopp ADCP WATR10
Continental ADCP WACA20, WATR20
WQM NRSROT, NRSESP
ECO-FL NRSROT, WACA20, WATR20
SBE19 v2 NRSROT, NRSESP, NRSNIN
Niskin carousel NRSROT

Site Codes:

NRSROT – Rottnest Island National Reference Station.

NRSESP – Esperance National Reference Station, (closed).

WACA20 – Western Australia, Canyon, 200m.

WACANO – Western Australia, Canyon North, 500m, (closed).

WACASO – Western Australia, Canyon South, 500m, (closed).

WATR05 - Western Australia, Two Rocks, 50m

WATR10 - Western Australia, Two Rocks, 100m

WATR15 - Western Australia, Two Rocks, 150m

WATR20 - Western Australia, Two Rocks, 200m

WATR50 - Western Australia, Two Rocks, 500m

The Seabird SBE39 measures and logs temperature and is used on all moorings except the designated ADCP moorings. The sampling rate used is usually set to five or ten minutes. The instrument is held in brackets attached to the mooring line. Several units are usually deployed on each mooring to obtain a temperature record throughout the water column. The SBEb39 variation also logs pressure.

The SBE37 is a multiple sensor instrument. Parameters measured are conductivity and temperature with options for oxygen and pressure.

The RDI profiling current meters measure water velocity at intervals throughout the water column. They are moored close to the sea-bed and project acoustic ‘pings’ upward and detect any reflected signals. These signals are processed and velocities measured using the Doppler theory. The velocities are measured at programmed intervals along the water column.

Three instrument variations are used according to the depth of operation. The Workhorse Sentinel 600 operates at a frequency of 600kHz and is used for the shallow 50m moorings. The Workhorse Sentinel 300 operates at 300kHz and is used for the intermediate 150m moorings. The Long Ranger operates at 75kHz and is used for the deeper 500m moorings.

The Nortek acoustic doppler current profiling meters are used as alternatives to the RDI instruments. They are attached at the bottom of the moorings looking upward. The Aquadopp operates at a frequency of 400kHz and is used in the 100m moorings The Continental operates at a frequency of 190kHz and is used in the 200m moorings. Like the RDI instruments they also measure temperature and pressure.

The Wetlabs Water Quality Meter measures temperature, salinity, dissolved oxygen, chlorophyll fluorescence and turbidity.  It is set up to sample for two minutes every fifteen minutes and is used on the NRS moorings. It requires a separate power supply and therefore, it is mounted in a frame with a battery unit.

The Wetlabs Environmental Characterization Optics fluorometer is used to measure chlorophyll-a, which is an indicator of active phytoplankton biomass and chlorophyll concentrations. The 200m moorings are designated biological measurement moorings and as such have the ECOs.

The Seabird SBE19plus v2 CTD measures conductivity, temperature and pressure with an optional oxygen sensor. It is used in profiling mode, sampling and logging the measured parameters on board at a rate of 4Hz.The measured parameter values can be directly compared with values obtained in the laboratory from seawater samples captured in Niskin bottles. These measurements are part of the BGC measurements taken periodically, one month, at the NRSROT site. The CTD values are post-processed according to the standard procedures, “National Reference Station Bio-Geochemical Sampling ANMN Standardised Profiling CTD Data Post-Processing Procedures v.1.5.”